1. Technical Field
The invention relates to an air spring, and in particular to an air spring having an outer rigid restraining cylinder which extends along the flexible bellows of the air spring. Even more particularly, the invention relates to the resilient mounting of the restraining cylinder to the air spring.
2. Background Information
Pneumatic springs commonly referred to as air springs, are used for many applications including motor vehicles to provide cushioning between movable parts of the vehicle, primarily to absorb shock loads impressed on the vehicle axles by the wheels striking an object in the road or falling into a depression. The air spring usually consists of a flexible rubber sleeve or bellows containing a supply of compressible air and usually will have a piston connected to an open end of the bellows and movable with respect to an opposite member and the bellows. The piston causes compression and expansion of the air within the bellows as the bellows compresses and expands as the vehicle experiences the road shock. This bellows is formed of a flexible elastomeric material containing reinforcing cords and permits the piston to move axially with respect to an end cap secured within an opposite open end of the sleeve from the piston.
Rigid or semi-rigid restraining cylinders are becoming more prevalent for air spring applications as the size of the air spring decreases to fit within the available space and the desire for longer durability. These restraining cylinders are usually mounted on the upper end member of the air spring and extend co-axially along the bellows to prevent excessive radial movement of the bellows during compression and expansion of the air spring. The cylinders also prevent the bellows from becoming damaged by contacting adjacent vehicle components.
One problem encountered with the use of these outer restraining cylinders is the attachment of the cylinder to the air spring end member. One common attachment is a radiator-type clamp or various types of swage rings which securely clamp the upper end of the cylinder to the end member. This is satisfactory for some applications where there is very limited tilting or arcuate movement of the air spring. Likewise, where the restraining cylinder has some flexibility, this decreases this flexing problem. However, the type of attachment is critical where a rigid cylinder, such as one formed of metal, is utilized since it provides little, if any, arcuate movement to the air spring without subjecting the cylinder and/or internal bellows to possible damage.